The goal of this research project is to investigate the molecular structure of mammalian DNA polymerases in order to have a better understanding of the biological roles, regulation and interrelationships between several classes of the mammalian DNA polymerase. The specific aims of this project are as follows: 1) Purification of various DNA polymerases from rat liver and regenerating rat liver. 2) Preparation of antisera against various DNA polymerases from rat liver. 3) Studies on the common subunits present in various DNA polymerases by biochemical and immunological methods. 4) Investigation into the biological reasons for multiple DNA polymerases in mammalian cells, and their roles in DNA replication.